XJR 1250 installation

[T Legg]

 I'm installing an XJR engine into one of my bikes. I've taken measurements from the standard FJ motor and marked the head fins of the new engine with the dimensions of the FJ head so I can shave the fins down to fit into my frame. It seems to me I have to shave five fins down on the back corners of the engine and two fins down on the front corners. I don't think I have to worry about the extra width of the fins
on the sides of the engine where the frame isn't close to the engine.
  Can any one out there who has one these engines in there bike post some pictures of the head and cylinder modifications that needed to be done ?

[Pat Conlon]

I have a Curt Andrews XJR block (sleeved) and XJR head on my '84 and I don't remember seeing any evidence of shaved cooling fins.....I'll check this afternoon.

[giantkiller]

Isn't the sprocket output shaft offset to the outside on the xjr. I seem to remember that they have a different sprocket cover. If so  a good time to switch to a wider rear wheel. I have an xjr block too but I think he is only worried about the finns on the head.
How did you  come by an XJR motor in the US? I thought they were never imported.

[RPM - Robert]

He has the offset sprocket and xjr sprocket cover already. You have to shave the cylinder head down to the same shape as the 1200 head, at least on the front side. If you want it symmetrical you do it on the rear of the fins as well. Not at the shop right now so no photos, but only the outer fins need to be reduced.

Pat, we painted then ground yours down. I had to do someone else's too but I don't remember now I made a template off the 1200 head. Probably long lost now.

When they were still available they were imported from 1999-2017. When the XJR was no longer available the race cars went to the FZ09 (legends car) and the Hayabusa (thunder roadster). They were imported for the race cars only. We were getting them until they stopped making them. I want to say a brand new 1250
Was around $5,500 maybe even $5,000

[giantkiller]

Didn't know that. Thanks Robert. Have to go take a look at mine.

[Pat Conlon]

Pat, we painted then ground yours down......

Good job Robert, I could not see any difference...

[RPM - Robert]

First photo is the square XJR head, second and third are the FJ1100/1200 heads. The XJ1200 heads were also square.

The overall width is the same at the bottom of the head it is just radiused and tapered a bit to make it look a bit cleaner. I think if you just radius the head without the taper you could get it in.

[T Legg]

Thanks Robert.
              Here is a picture of an fj head next to an xjr .

[T Legg]

A picture of the taper.

[giantkiller]

Is there any difference other than the fins?
Larger valves, different compression. Etc.

[RPM - Robert]

No. They have EGR ports on some of the 1250/1300 years. Other than that, they are the same.